There is an optical waveguide element including a substrate that has an electro-optic effect and an optical waveguide provided in the substrate. For example, in optical modulation elements described in Patent Literature No. 1 and Non Patent Literature No. 1, the optical modulation bandwidth is expanded by polarization reversal of a part of the substrate provided with the optical waveguide. In addition, in an integrated optical modulation element described in Patent Literature No. 2, a high-accuracy optical signal with zero chirp and no skew is generated by reversing the polarization of apart of the substrate provided with the optical waveguide. Meanwhile, in order to reduce the drive voltage and expand the bandwidth, an optical modulation element whose waveguide is covered with a ridge waveguide structure is known and widely used.